HighPROTEC MRDT4 differential protection of two-winding transformers
HighPROTEC MRDT4 is a digital differential protection terminal for two-winding transformers with a set of backup protections. It is also used as an economical generator differential protection, including with a step-up transformer in the protection zone.
- Application
- two-winding transformers; generator (including with a unit transformer)
- Differential protection
- biased, detection of transients and CT saturation, connection group selection, zero sequence elimination, three-point characteristic, high-set stage
- Earth differential
- 2 stages
- Backup protections
- 4 overcurrent stages, 4 earth fault stages, 2 asymmetry stages
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
The functions of MRDT4 from the HighPROTEC line are chosen for two-winding transformers. The differential protection is a biased one, with recognition of transients and current transformer saturation, with selection of the winding connection group and elimination of the zero sequence component. The trip characteristic has three points, and there is an unrestrained differential high-set stage. Differential earth fault protection has two stages, also with a three-point characteristic and a high-set stage. The protection functions are adapted to VDE-AR-N 4110:2023-09.
The backup part consists of four stages of non-directional overcurrent and short circuit protection and four stages of non-directional earth fault protection. The characteristics can be chosen from DEFT, ANSI (NINV, VINV, EINV), IEC (NINV, VINV, LINV, EINV), RXIDG, Thermal Flat, IT, I2T, I4T. Two more stages protect against load unbalance. A thermal model monitors transformer overload. Signals from the gas relay (sudden pressure rise), oil temperature and additional temperature are wired to digital inputs, and the winding temperature can be measured with an external RTD unit.
Supervision covers current transformers, breaker failure protection, the trip circuit, cold load pickup and switch onto fault. The relay measures THD, current vectors and angles, RMS and fundamental values, symmetrical components and differential currents. The terminal controls two devices, circuit breakers, disconnectors or earthing switches, and keeps a record of circuit breaker wear.
The hardware is built on a dual-core processor. The Modbus, Profibus, DNP3.0, IEC 61850, IEC 60870-5-103 and IEC 60870-5-104 protocols support individual data point assignment, time is synchronized via SNTP and IRIG-B, and cybersecurity functions are included. Non-volatile recorders store waveforms for 120 s, 20 faults, 300 events and a trend of 4000 records. Up to 80 logic equations extend protection, control and monitoring, and the relay menu switches between 8 languages. Type tests were carried out in KEMA laboratories to the requirements of IEC 60255-1:2009, and CSA-C22.2 No. 14, UL508 and EAC certificates are available. The full set of functions, Smart view and waveform analysis are supplied at no extra charge under the all-inclusive concept. The terminal is installed on 6–110 kV transformers of distribution and industrial substations, and on transformers of power plants and renewable energy facilities.
Technical specifications
| Application | two-winding transformers; generator (including with a unit transformer) |
|---|---|
| Differential protection | biased, detection of transients and CT saturation, connection group selection, zero sequence elimination, three-point characteristic, high-set stage |
| Earth differential | 2 stages |
| Backup protections | 4 overcurrent stages, 4 earth fault stages, 2 asymmetry stages |
| Process signals | gas relay, oil temperature via digital inputs, external RTD unit (option) |
| Devices | 2 |
| Recorders | 120 s / 20 / 300 / 4000 |
Request a price and lead time
HighPROTEC MRDT4 differential protection of two-winding transformers. We reply within one business day.
Or email sales@usk.ua or call 044 339-50-20.
Customs codes
| UKTZED (Ukraine) | 8537 10 98 00 |
|---|---|
| HS, 6 digits | 8537 10 |
| CN (EU) | 8537 10 98 |
| HTSUS (USA) | 8537 10 91 70 |
| China customs tariff | 8537 10 90 90 |
Codes are for reference: the final code is determined at declaration for the specific model.
Questions and answers
Can MRDT4 be used for generator protection?
Yes, MRDT4 is used as an economical generator differential protection. A step-up transformer can be included in the protection zone.
How does MRDT4 behave during inrush current and CT saturation?
The differential protection is biased and recognizes transients and current transformer saturation. The characteristic has three points, and an unrestrained high-set stage is provided separately.
Can a gas relay and oil temperature sensors be connected to MRDT4?
Yes, signals from the gas relay and oil temperature are wired to digital inputs. The winding temperature is measured with the optional external RTD unit.
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